Electrical heater



Sept. 26, 1933. R. A. SHIRLEY ELECTRICAL HEATER Filed April 24, 1951 autumna L Patented Sept. 26, 1933 PATENT OFFICE ELECTRICAL HEATER Richard A. Shirley, Indianapolis, Ind., assignor to W. H. Johnson & Son 00., Indianapolis, Ind, a corporation of Indiana Application April 24, 1931. Serial No. 532,475

2 Claims.

The present invention relates to an electrical heater, and more particularly to a portable space heater of the type which comprises an electrical heating element and a means for causing a current of air to flow over said element.

The prima'ry object of the invention is to pro- .;vide a compact, neat, and highly efficient unit .of the character described which shall be free from undesired turbulence in the current of air passing through the unit, but which shall be so designed as to effect considerable turbulence and diffusion of the current of air issuing from the unit. Further objects of the invention will appear as the description proceeds.

To the accomplishment of the above and related objects, my invention may be embodied in the form illustrated in the accompanying drawing, attention being called to the fact, however, that the drawing is illustrative only, andthat change may be made in the specific construction illustrated and described-so long as the scope of the appended claims is not violated;

Fig. 1 is a perspective view of the rear face and one end wallof a unit constructed in accordance with the present invention;

Fig. 2 is a substantiallycentral vertical section through said unit, parts thereof being shown in elevation; and s Fig. 3 is a broken front elevation of the heat ing and radiating unit, per se.

Referring more particularly to the drawing, it will be seen that I have illustrated a unit comprising a cabinet indicated generally at and formed to provide a substantially plane front wall 11 and a substantially plane rear wall 12, there being provided a flange 13 projecting for- Wardly from the plane of the wall 11 adjacent the base thereof, and a flange 14 projecting rearwardly from the plane of the rear wall 12 adjacent the base thereof.

The front wall 11 is formed with an aperture 15, preferably circular in form, and the rear wall 12 is formed with a co-axial aperture 16, likewise preferably circular. A casing 17, preferably substantially cylindrical in form, is provided adjacent its rear end with an outwardly turned flange 18, and saidcasing is provided at its opposite end with an outwardly flared flange 19.

The flange 13 is secured to the wall 12 by a plurality of bolts and nuts 21, or other equivalent fastening means, said bolts passing through the wall 12, a grille 22 suitably secured to said wall in a position to cover the aperture 16, and said flange 18. The grille 22 is provided pri- (Cl.v 21939) marily for the purpose of improving the appearance of the unit.

A grille 23 is suitably secured to the inner surface of the front wall 11, preferably by brazing, or the like, in a position tocover the aperture 15. The casing 17 is so proportioned and positioned that the flange 19 abuts the inner face of the grille 23. It will thus be apparent that the easing 17 provides a substantially straight-walled conduit connecting the apertures 16 and 15, thus 65 eliminating any possibility of turbulences in the air current therethrough, set up in corners or backwashes.

The heating unit is indicated generally at 24 and, as is clearly shown in Fig. 2, is positioned primarily within the casing 17 and immediately to the rear of the grille 23. Said unit comprises a heating element proper consisting of a closed, annular, metallic housing 25 forming a chamber within which is received an electrical resistance unit indicated at 25. Said resistance unit may be of any suitable known type. A conductor cable 2'? enters the cabinet 10 and extends therethrough, outside of the conduit formed by the casing 17, to a point adjacent the 0 heating unit, where it passes through a bushing 28 to the interior of said conduit. Contact between the wires of the cable 27 and the resistance unit may be made through binding posts 29 clamping contactors properly in position on said resistance $5 unit.

The element 25 is formed of metal of a high radiating efficiency, and a series of radiating fins 30 surrounds said element, fins contacting, at their inner ends, the outer periphery of said 590 element 25. A binding strip 31 engages the outer ends of said fins 30, and a pair of cars 32 project radially from said strip, said ears being clamped together by a bolt 33 and a nut 34, whereby said fins 30 are held in position on said 95 element 25. Preferably, the fins 30 take the form of a continuous strip, rebent in the manner illustrated specifically in Fig. 3.

A second series of fins 35 is positioned with the outer ends of the fins in contact with thegjoo inner periphery of the element 25; and a block 36 is received in contact with and supported by the inner ends of the fins 35. Said block 36 may preferably take the form of a hollow, cylindrical, metallic casing.

A bracket 37 is secured to the casing 17 by means of one or more bolts 38, and said bracket supports a motor 39 substantially in co-axial relation within the casing 17. Said motor 39 has secured to its shaft a propeller 40 arranged tog-110 drive a current of air over and through the heating unit 24. As will be obvious, the block 36 is positioned substantially in coincidence with the comparatively dead portion of the air current created by the fan 40, so that all of the current is forced to flow over the element 25 and the fins and 35. A cable 41 having the usual plugfitting 42 at its free'end enters the cabinet at the point 44, and is suitably connected toprovide current to drive the motor 39 and to heat the resistance unit 26. The cabinet may preferably be provided with a carrying handle 43.

It will be obvious that, when current is supplied through the cable 41, the heating element 24, as a whole, will be heated by conduction from unit 26, and the fan will be driven to force a current of air over and through the heating unit 24. The stream of air, as it issues through the interstices between the fins 30 and 35,'encounters the grille 23, and is diffused thereby so that, instead of a strong and concentrated blast of hot air issuing from the heater, there issues a diffused and turbulent stream which stimulates circulation throughout the space in which the unit is in use. The resistance unit 26, being completely enclosed and substantially protected from contact with air, is unusually'long lived, and the heating efficiency thereof is materially increased by theprovision of the fins 30 and 35.

"Because of the-provision of the dead air spaces between the casing 17 and the outer'walls of the cabinetiO, the cabinet walls are relatively cool, so that the unit may readily be handled and moved from place to place without danger of burning; and so'that the unit may be located elose to the-most delicate finishes without substantial probability of harm resulting to such finishes.

Theprovision of the flanges 13 and 14 is a further safety measure. The heating element, after long continued operation, attains a high temperature. In case the unit is disconnected after a long period of operation and then is laid face down on the floor or other surface, or is acci- -dently knocked over, the flange '13 holds the grille 23 off the floor, and a current of air is automatically set up flowing upwardly through the grille '23, over the heating unit 24, and so through the casing 17 and out through the grille 22. In the absence of the provision of the flange l3, material damage would, of course, be done under the circumstances outlined above. It is also possible that the unit may be overturned at a time when the fuse in the motor line has blown out, or when, for any other reason, the heating element is energized but the motor is not. Under such circumstances, of course, the abovedescribed upwardly-moving air current will be set up, thus minimizing any damage to the surfaceon which the unit is resting.

I claim as my invention:

1. A portable space heater comprising a cabinet having a plane front wall formed with a port therethrough, a forwardly projecting flange on said front wall, and a plane back wall having a porttherethrough in alignment with said firstmentioned port, means in said cabinet providing a straight-walled passage connecting said ports, and'an electric heating elementwithin saidpassage adjacent said front wall, said flangeprojecting forwardly substantially parallel with the axis of said passage whereby, when said heater is disposed upon a supporting surface with itsfront wall presenteddownwardly, a space is provided between said surface and said front wall resulting in the creation of an upward draft through said passage to protect such surface from damage by said heating element.

2. A portable space'heater comprising a cabinet having a plane front'wall formed with a port therethrough, a forwardly projecting flange adjacent the base of said front wall, a plane'back Wall having a port therethr'ough in alignment with said first-mentioned port, and a rearwardly projectingflangeadjacent the base of said back wall, means in said cabinetproviding a straightwalled passage connecting said ports, and an electric heating element within said passage edja'cent said front'walLsaid'flanges being'effective to preventdirect-contact of the whole surface of said front wall or of said back wall with a supporting surface.

RICHARD A. SHIRLEY. 

